1. Field of the Invention
The present invention relates generally to excavating equipment, and in a more particular sense has reference to a backhoe bucket, having on its leading or digging edge a series of digging tooth units, each of which is power driven, and each of which is further individually controlled with respect to the air supplied thereto and its advancement toward a work surface that is to be broken up and loaded into the bucket.
2. Description of the Prior Art
Heretofore, it has been proposed to provide a backhoe bucket or similar excavating device, having a row of power driven digging teeth.
The prior art suggests the provision of pneumatically powered teeth reciprocated at high speed, as for example by an air hammer. In such devices, the advancement of the teeth into the work surface has resulted entirely from the bodily movement of the backhoe bucket toward said work surface. This has produced disadvantages, in that some or all of the digging teeth may encounter surfaces too hard to be broken up when the entire series of teeth are simply forced against the work by the pressure of the bucket alone.
The prior art, thus, has been deficient in respect to efficiently controlling the advancement of each tooth, independently of the other teeth, into the work surface, in a manner whereby exceptionally hard material encountered by one tooth will not detract from the ability of the other teeth to continue advancement into the surface that is being broken up and removed. And, the prior art has included no provision whereby one or more teeth that may be encountering unusually heavy resistance to penetration, will be advanced into the work at a rate of speed that will assure breaking up of the work surface thereby in the shortest period of time and with the maximum efficiency.
Another characteristic of prior art machines may be noted, in that machines of this type have not been energy-efficient. In those machines in which there are individually powered digging teeth, all the teeth continue in operation whether or not resistance is being encountered thereby. As a result, the output of compressed air to the teeth has been maintained at an undesirable, maximum level. This points up the obvious desirability of providing a machine of this type in which the use of compressed air is kept to a minimum, and is permitted to occur only when the compressed air is being utilized to advantage.
In similar devices in the prior art, further, the digging tooth assemblies have been placed under undesirable strain, in that no special provision has been made to protect the digging teeth when they are not being reciprocated by their associated air hammers. It is accordingly desirable to overcome this deficiency of the prior art by incorporating means which will automatically shift the teeth to retracted positions when power to their associated air hammers is cut off.
It is proposed, in carrying out the present invention, to overcome the noted prior art deficiencies, through the provision of a backhoe bucket having pneumatically powered teeth each of which, while being reciprocated at high speed by an associated impact hammer, will at the same time be moved forward continuously into the work independently of the other teeth.
It is further proposed to assure economy of operation to the maximum extent, through the provision of means that will cut off the supply of air to each individual tooth unit, whenever reciprocation of the tooth is unnecessary or undesirable, while assuring continued operation of those teeth in which high speed reciprocation remains productive.
Further, it is proposed to overcome the deficiencies of the prior art by incorporating means in each tooth unit which will retract the tooth automatically whenever power to the unit is cut off, thus permitting the bucket to operate as a conventional bucket of the type in which the teeth are permanently and immovably mounted adjacent the digging edge of the bucket.